18jan17:covering center of dish

Background:

investigating under the dish while transmitting, we saw arcs
on some of the vertical support posts around the center hole.

When transmitting at 5 MHz, large arcs were induced in the 8
Mhz element on tower 1.

Covering the center of the dish:

The large opening at the center of the bowl
would not allow currents to flow in the center of the dish.
We decided to cover the hole by stringing cables (3/8 inch) across
the hole in both directions. The spacing between the cables (in
both directions) was made much less than the wavelength (5 MHz:
60meters, 8 MHz:37.5 meters).

On 17/18 jan17 we covered the open hole with cables:

we strung 5 cables in the long direction of the
hole .. connecting them to panels at each end.

cables were strung along the short direction of the hole
(every 5 feet?). They were also connected to the panel edges.

Where the cables crossed, they were tied together
electrically using ubolts.

the cables were strung so that they did not touch the ao9
monument.

The monument stuck up above the cables.

the aluminum frame holding the ladders was below the cables.

The western portion the opening was already covered with the
long panels used to shield the receivers from the ground
radiation.

these long panels were only tied together at each end of the
long direction.